1. Field of the Invention
The present invention relates to a semiconductor device having a transistor including an oxide semiconductor film and a method for manufacturing the semiconductor device. Note that one embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the present invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. In addition, one embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter. Specifically, examples of the technical field of one embodiment of the present invention disclosed in this specification include a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, a lighting device, a power storage device, a storage device, a method for driving any of them, and a method for manufacturing any of them.
2. Description of the Related Art
Attention has been focused on a technique for forming a transistor using a semiconductor thin film formed over a substrate (also referred to as thin film transistor (TFT)). Such a transistor is applied to a wide range of electronic devices such as an integrated circuit (IC) or an image display device (display device). A silicon-based semiconductor material is widely known as a material for a semiconductor thin film applicable to a transistor. As another material, an oxide semiconductor has been attracting attention.
For example, a transistor including an oxide semiconductor containing indium (In), gallium (Ga), and zinc (Zn) as an active layer of the transistor is disclosed (see Patent Document 1).
Further, a technique of improving carrier mobility by forming stacked oxide semiconductor layers has been disclosed (see Patent Documents 2 and 3).